Compatibility and Differences:
34461A and 34401A
Digital Multimeters
Application Note
Introduction
The 34401A digital multimeter
(DMM) is the industry standard. Its
accuracy, ease of use, and flexibility
have attracted users for more than
two decades and its low cost of
ownership and high quality have
helped it to be one of the most
successful products in Agilent’s
history. Many engineers do not
even evaluate other DMMs when
they want to order one; they know
the 34401A will work for them. It is
an essential meter for bench and
automated test applications.
The 34461A DMM is the nextgeneration 34401A. This new DMM
was designed by the same group as
the 34401A, with many of the same
R&D engineers participating. With
this continuity of experience and
expertise, Agilent has made a DMM
that is a virtual drop-in replacement
for the 34401A while continuing to
improve usability and measurement
technology.
The 34461A is a compatible 34401A
replacement with few exceptions. If
you are looking to migrate from the
34401A to a 34461A and want to fully
understand all differences between
the two models, this application note
will help you. Our goal is to help
you migrate from your 34401A to a
34461A effortlessly.
Compatibility
There are many factors to keep in mind when you want to replace reliable
instruments such as the 34401A. Here are just some of the areas where the
34461A is equivalent to the 34401A.
• Functions and ranges: The 34461A is a superset of the 34401A capability.
Differences are listed below.
• Measurement accuracy and resolution: The 34461A’s specifications and
typical characteristics are as accurate or better than those of the 34401A.
See Table 1. All specifications are ISO17025 compliant.
• SCPI compatibility: We have taken extra care to ensure that the 34461A will
work with SCPI programs that were written for the Agilent 34401A.
Programming considerations and differences are listed below.
• Mechanical size: Height and width dimensions are the same.
• Accessories: Rack mount kits and probe accessories are compatible with both
products.
• Manufacturing: Both DMMs are produced to the same rigorous quality
standards and manufacturing process controls.
• Service and support from Agilent: Our international team is available to help
you calibrate your DMM or answer any questions about either instrument.
• Warranty: Both the 34401A and 34461A offer the same outstanding 3-year
standard warranty.
Table 1. Key features and model comparison
34461A
34401A
6½ digits
6½ digits
Front and rear
Front and rear
1-year DCV accuracy
± (% of reading + % of range)
0.0035 + 0.0005
0.0035 + 0.0005
Measurement speed @ 4½ digits
1000 readings/s
1000 readings/s
Resolution
Input terminals
Measurements
DCV, ACV, Resistance,
Frequency, Period, Continuity
Same
Diode
AC and DC current
5V
1V
100 μA – 10 A
10 mA – 3 A
Temperature
RTD/ PT100, thermistor
N/A
Reading memory
10,000 readings
512 readings
Number, histogram, bar meter,
trend chart
Number
USB, LAN Optional: GPIB
GPIB, RS-232
Display
Connectivity
Measurement Tip
Use SCPI compatibility mode
By default, the 34461A *IDN? query returns:
Agilent Technologies,3446xA,
<Serial Number>,ff.ff-pp.pp-mm.mm-gg.gg-bb-pp
For compatibility purposes, use SYSTem:IDENtify HP34401A to return:
HEWLETT-PACKARD,34401A,<Serial Number>,ff.ff-pp.pp-mm.mm-gg.gg-bb-pp
You can also configure this from the front panel:
[Utility] > System Setup > User Settings > SCPI ID
Differences
The few differences between the 34461A and 34401A that might affect migration are listed below. Many of these differences improve the performance of the 34461A relative to the 34401A.
Physical differences
• The 34461A is not as long as the 34401A, and the connectors are in different positions.
• The 34461A does not support RS-232, and GPIB is optional on the 34461A.
• The 34461A does not support hardware limit test outputs.
2
Key measurement differences
• The 34461A and 34401A use different calibration procedures, with different default passwords.
• Some specifications vary between the 34461A and the 34401A. In general, the 34461A specifications equal or exceed
those of the 34401A. One exception: the 34401A’s 3-A range is slightly better than the 34401A. For best current measurement results above 1 A, use the 34461A’s 10-A input terminal.
• The 34461A has additional current ranges: 100 µA, 1 mA, and 10 A. Therefore, the MIN and MAX parameters produce
different results. In addition, autorange on the 34461A may use different ranges than on the 34401A, and autoranging
may take longer.
• Burden voltage is generally lower on the 34461A than the 34401A.
• 34461A uses a digital AC measurement technique. This produces better linearity and a sharper bandwidth roll off for AC
measurements.
Key programming differences
• The 34461A does not support the older 3478A or Fluke 8840A programming languages.
• The INIT command on the 34401A is non-overlapped, except when bus triggering (*TRG) is selected. This means that
CONF:VOLT:DC;:INIT;:CONF:CURR:DC;:INIT makes two measurements. The INIT command on the 34461A is overlapped,
and the above sequence generates an error message.
• By default, the 34461A *IDN? query returns:
Agilent Technologies,3446xA,<Serial Number>,ff.ff-pp.pp-mm.mm-gg.gg-bb-pp
• The 34461A parses and executes commands faster than the 34401A. The 34461A also supports overlapped command
processing between INIT and measurement completion. Proper synchronization with *WAI and *OPC? minimizes the
impact. Existing systems that depend (intentionally or unintentionally) on 34401A command execution speed for timing
may experience subtle timing issues.
• The 34461A requires less settling time than the 34401A, yielding shorter default trigger delays. Therefore, if you use
default trigger delays, these delays may start a measurement before your DUT has settled, which means that a signal
that was fully settled when measured on the 34401A will still be settling on the 34461A.
• The 34461A and the 34401A may generate different error messages. This is usually not a problem, because existing
programs normally do not generate SCPI errors.
• The 34461A can store up to 10,000 readings, which is more than the 512 that the 34401A allows. This is unlikely to affect
existing programs.
• The 34461A defines bits in the questionable data and status byte registers that were unused by the 34401A. Programs
that properly mask unused bits will minimize issues associated with querying these registers.
• Under certain conditions, the 34461A may return and display negative resistance values. For details, see [Help] >
Negative Resistance Values from the front panel.
• The 34461A always puts readings into memory. When the READ? query finishes, a subsequent FETCh? returns those
same readings. In a similar situation, the 34401A shows memory as empty. Also, if the computer is not taking readings
fast enough, the 34401A slows down to avoid losing readings. The 34461A does not allow the computer to pace its
reading rate.
• To support testing a wider range of diodes, the compliance voltage has been increased from 1.2 V to 5.05 V. The range for
the 34461A is fixed at 10 V, as opposed to 1 V on the 34401A. The current source remains fixed at 1 mA.
• The dBm reference on the 34461A is a volatile value. It was non-volatile on the 34401A.
3
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Conclusion
The 34461A DMM is the nextgeneration 34401A. When you
migrate from the 33401A to the
33461A DMM, you do not need to
rewrite your programs or spend
hours learning a brand-new,
complicated interface.
Three-Year Warranty
www.agilent.com/find/ThreeYearWarranty
Agilent’s combination of product reliability
and three-year warranty coverage is another
way we help you achieve your business goals:
increased confidence in uptime, reduced cost
of ownership and greater convenience.
myAgilent
The 34461A DMM lets you:
Display DMM results in ways you
never have before
Measure with unquestioned confidence
Move to the next-generation 34401A
with 100% assurance
Learn more about the 34461A at
www.agilent.com/find/Truevolt
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Published in USA, May 2, 2013
5991-2367EN
MEASUREMENT BRIEF
Viewing Graphical Results
on a DMM Display
Snapshot
A company designing a high-power
solar charger for smart phones
and tablets needed to rigorously
test the circuit that detected low
solar-cell power for shutting down
and restarting the charging circuit
smoothly. This circuit was necessary because the charger had no internal battery to act as a buffer. To simulate
changing solar radiation, the design team used a triangle waveform from an arb/
function generator as a source.
Introduction
ntroduction
Digital multimeters measure and display various parameters such as
voltage, current, resistance, and temperature in an easy-to-read number
format. However, many times you are looking for more than a single
reading in the display. Often, the really meaningful information lies in
the trend or statistics of a series of readings. If your DMM offers connectivity, such as LAN or USB ports, you can transfer your readings to
a computer for computation and display. But transferring data to a PC
may take more time than you want to spend.
Now, a new DMM, the Agilent 34461A, offers a way to get insight
into your measurement data without transferring your data to a PC. The
34461A features a large graphical display and built-in math functions
that show measurement trends, statistics, and histograms all in a single,
compact unit.
The engineers set up the Agilent
34461A to measure the on/off output
voltage of the detector circuit and
displayed the results using the histogram mode. At frequencies below
one Hertz, the display clearly showed
a binary distribution, which was the
desired result.
However, they found that for higher frequencies, which occurred when they
waved a hand across the solar panel, the circuit exhibited an anomaly that
caused an intermediate output value. This anomaly clearly interfered with the
proper output charging operation.
A relatively simple design change to
the cutoff frequency in the detector
circuit solved the problem and
eliminated potential customer warranty claims.
Display DMM results in ways you never have before
Four different display modes give you fast insight
Trend chart
Number display
Bar meter
The 34461A’s simple, intuitive user interface gives you quick and
intuitive access to different views of your data. You can easily access the
structured display and math menus with a single key on the front panel.
The menu options appear on the soft keys under the display. The six soft
keys and a set of navigation buttons on the front panel eliminate the need
for an external computer and software.
Figure 1. When you press the Display button, the soft keys show
the choices available for the different display modes.
Info at a glance saves time
Histogram
A trend
rend chart shows direction
If you expect a measured parameter to remain constant, you only need to
measure it once. But in the real world, values drift with time, track other
parameters, or vary in complex ways with outside influences. You can set
the trend chart display on the Agilent 34461A to display the most recent
data over the last minute, or all the data collected since the last time
the readings were cleared. You could use this innovative capability, for
example, for monitoring a power supply design under changing loads. You
would set up multiple DMMs to monitor vthe output voltage, load current,
and various temperature points inside the unit. As the load current is
varied, you could see the change in voltage and temperature as a function
of time.
The bar meter display is ideal for showing an analog indication of the value
in addition to the digital readout. Sometimes you just need a quick qualitative glance at a measurement to be assured that the test is proceeding as
you planned. The bar meter also can be enhanced with the limits function
in the Math menu to provide an even more informative display.
Figure 3. A trend chart shows you changes in your measurements
over time.
Histograms tell all about the data
Figure 2. The bar meter display gives you a quick qualitative view
of your measurement.
2
Display Measure Move
When the lowest digits of a reading are changing constantly, it is important to know the nature of that variation. The histogram provides insight by
showing the distribution of the measured values. The average, distribution
shape, and standard deviation are all critical information for understanding
the variation phenomena.
The histogram binning can be automatic set or you can set it to values of
10, 20, 40, 100, 200, or 400, depending on your need for resolution of
the display. You can set up outer bins to catch values that occur outside
the histogram range. This can give you insight into the occurrences of
occasional outside influences such as power glitches or EMI from other
equipment.
Figure 4. A histogram shows the distribution of your measured values.
Adding math to displays brings data
to a new level
Null is most useful for zeroing out lead resistance when you measure
small values of resistance. You can also set other measured values such
as voltage or temperatures as null values simply by pressing the Null
front-panel key so that deviations from the measured value can be easily
observed. If you have predetermined a null value, you can enter that value
using the arrow keys. There is no need to make a measurement first.
Statistical data displays are always available for the readings in memory or
you can clear readings to start a new series of statistics on collected data.
These statistical data are especially useful for determining the stability of
a measured value and also for detecting outlying data via the min/max
displays.
Figure 7. Use the statistical display to determine the stability of a
measured value.
Limits provide both a visual indicator and an audio “beeper” tone to alert
you when a preset condition has been exceeded. For example, if you are
monitoring internal temperatures on prototype circuits in a heat-soak oven,
it is critical to get a warning before a valuable prototype overheats and
suffers damage. You can set and apply limits to all four display modes for
maximum flexibility in measurement readout.
Figure 5. Setting null values is easy on the front-panel display.
When the range of measured values exceeds a decade or more,
dB/dBm scaling provides a convenient logarithmic readout relative (dB)
to a user-set reference. Or to see an absolute value (dBm) referred
to 1 mW across a given resistance value, simply select a value ranging
from 50 to 8000 ohms, using the front panel.
Figure 8. An example of limits with the trend chart.
Conclusion
Figure 6. Automatic scaling provides a convenient logarithmic
readout relative to a user-set reference.
MEASUREMENT TIP
Digit masking
If you are displaying
noisy signals where
the lowest digits
constantly change,
use the 34461A’s
digit masking feature
to show just the
resolution you need.
#
1
Whether you are measuring a parameter on a single point or multiple
points, it is clear that a single value does not provide much insight into the
performance of your DUT over time or in response to outside interference.
Setting up a computer connection for data collection and analysis often
takes too much time and can delay the testing schedule. Now with the
new Agilent 34461A DMM’s graphical display and built-in math functions,
the most useful time-cumulative and data-cumulative analysis results are
available at your fingertips, using simple front-panel menu entries. You can
meet your testing goals faster than ever before.
See following page
for additional
Measurement Tips
3
MEASUREMENT TIP
#
2
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Labeling your signals
When you have several DDMs on the bench or in a rack measuring a variety of points and parameters, the usual solution for
identifying them is a taped-on label or adhesive-backed note.
Now you can add the label to the display using the front-panel
keyboard. These labels remain in memory even after a poweroff situation and they never fall off the unit.
For more information on Agilent Technologies’
products, applications or services, please contact
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United States
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MEASUREMENT TIP
#
3
Alternate views of the data
It’s important to know that the display view initially chosen is
not the only way to look at the data in memory. You can switch
back and forth between display views and math applications as
required. For example, you
can start with the Trend Chart,
Recent display of the last minute of data, then switch to All
to view all data collected, and
later switch to the Histogram
display of all data.
Other capabilities include
the Math, Statistics function
where you can also see
the average and standard
deviation of the
histogram
m data.
1 800 629 485
800 810 0189
800 938 693
1 800 112 929
0120 (421) 345
080 769 0800
1 800 888 848
1 800 375 8100
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(65) 375 8100
Europe & Middle East
Belgium
Denmark
Finland
France
32 (0) 2 404 93 40
45 45 80 12 15
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0825 010 700*
*0.125 €/minute
Germany
Ireland
Israel
Italy
Netherlands
Spain
Sweden
United Kingdom
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For other unlisted countries:
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Product specifications and descriptions in this
document subject to change without notice.
© Agilent Technologies, Inc. 2013
Printed in USA, March 30, 2013
5991-2226EN
MEASUREMENT BRIEF
No Programming Required:
Multisignal Capture and
Analysis with DMMs
Snapshot
Introduction
New Agilent software reduces the learning curve for DMMs and provides an
easy way to set up multiple Agilent DMMs to acquire your signals. In addition
to making it easier to set up multiple DMMS, Agilent’s new DMM Connectivity
Utility supports quicker instrument setups and faster data capture and visualization and addresses many of the difficulties you face in using digital multimeters.
The application supports older DMM models including the 34401A, 34405A,
34410A, and 34411A. It also supports our latest-generation 34450A, 34460A,
and 34461A DMMs. With this application, you spend more time using your
instrument and less time learning and troubleshooting it.
This measurement brief explores how the new Agilent DMM application can
help you acquire multiple signals in parallel and understand the data faster. It
helps you quickly synchronize measurements, graph measurements and export
data in a variety of common formats. First we’ll discuss how the DMM Connectivity Utility makes setting up communication with a DMM easier, then we’ll
look at how the application helps you understand your data with ease. We’ll
conclude with an example that shows how to use two DMMs to make simultaneous voltage and current drain measurements on your device.
An IC validation engineer needed to characterize a design for a linear
regulator. His task was to measure a regulator with an output voltage
range of 1 V to 3.3 V with an output current of 150 mA. His first step was
to ensure the voltage would stay constant (±0.5%) under varying load
conditions. After setting up the hardware for the test, he needed to be
able to log his V/I data. The engineer doesn’t like to program, but he is
familiar with the Agilent DMMs on his bench. He discovered the Agilent
DMM Connectivity Utility and learned about its multiple-signal capture
capability. With this utility, he was able to use a DMM to measure the
output voltage and one to monitor the load current at the same time.
Without writing any code, he characterized his V/I curve and discovered
the IC had a defect: every 60 seconds it deregulated for 500 ms. The engineer went back to the design team with graphical data from the Agilent
DMM Connectivity Utility and they agreed to investigate the defect.
An easier way to communicate with a DMM with I/O
Paired together with Agilent I/O Libraries, identifying DMMs connected
to your PC is easier than ever. Agilent’s new DMM Connectivity Utility will
automatically identify connected DMMs configured on your bus. This initial
opening view shows the model of DMM and the I/O address that it is
connected to. The app intuitively presents the DMMs as bench tiles. Each
tile’s launch button will initiate control and datalogging for each DMM.
You can control multiple DMMs within the app.
Making simultaneous voltage and current drain
measurements
In this example, we want to do a simple DCV measurement. Use the
Measurement menu to select the DC Voltage measurement function. The
context-sensitive Measurement tab now presents all the parameters you
would want to use for DCV measurements for your DMM. You can then
set up your second DMM to measure DC current in the second bench tile.
See Figure 2 to see DMM1 set up to measure DCV and DMM2 set up to
measure DCI.
Figure 1. View of connected DMMs using PC app
Make a measurements and understand the data without learning the whole instrument
Engineers are often time constrained and don’t necessarily want to spend
time on extraneous activities. If you want to make a simple DMM measurement, you want to ensure that the instrument is fully set up and not
missing a key parameter when running a test. Measuring multiple signals
can be especially painful if you aren’t familiar with the DMM or if you
have differing generations of Agilent equipment. Agilent DMM Connectivity Utility’s unified interface supports Agilent DMMs released in the last 25
years. The PC DMM app can communicate using RS-232, GPIB, USB, or
LAN. With this I/O flexibility you can now use the same intuitive interface
for all these DMMs.
Very few of us can look at a group of numbers and make quick, accurate
judgments on the data set. Graphing the data is preferable, but sometimes
it just takes too much effort to get a nice-looking chart that is easy to read
and understand. The Agilent DMM app can help you understand your
data visually, in real time, with time-stamped data. Its layout is intuitive
and graphs are aesthetically pleasing. The app also has numerical outputs
for those who need the raw data.
Figure 2. Configuration of two different DMMs shown side by side in the
DMM Connectivity Utility
The Data Logger/Digitizer tab presents you with more advanced functionality such as trigger menus, in-program limit testing, and digitizing setups.
This context-sensitive menu is dependent on your DMM model. New functionality allows you to set up the apps to email you when a measurement
fails a limit. Let’s set the triggering for both to be immediate triggering (you
could also use an external trigger). Figure 3 also shows that we are stopping after 1 minute of sampling. You can set up the acquisition to sample
indefinitely. That’s all there is to setting up the synchronized sampling.
Agilent’s DMM Connectivity Utility presents the full setup for given measurement functions. The app intuitively presents the DMMs as bench tiles.
With this new app, you can now visualize the outputs of up to four different DMMs. The application has the ability to control and get measurements with up to 9 DMMs at a time. An intuitive bench layout allows you
to see your virtual bench in a single, double, or four-tiled view.
To change parameters for each DMM, press the configuration wrench
in each tile. This brings up the Measurement menu and the Data Logger
menu in tabbed windows.
Let’s go through a simple example that is a common test on many
benches: measuring voltage and the current drain from a device.
2
Display Measure Move
Figure 3. Trigger menus
To start gathering data, press the Start All Acquisitions key. This will
automatically trigger all instruments you have set up. It also synchronizes
measurements whether you are in single-tiled or multi-tiled bench mode.
The data log chart is updated in real time, and you can see that the data
points line up. The time stamp feature shows the time when the sample
was taken. This allows for a quick understanding of measurement peaks,
noise, or drift. Figure 4 shows the chart view of DMM1 (DCV) and
DMM2 (DCI). This visualization allows us to understand the relationship
between the two measurements graphically. You can control your DMMs
and visualize the synchronous measurements in one program.
The example we are using had different integration cycles for the two
measurements, but how does this affect the data? Exported data, as
shown in Excel in Figure 7 shows that the samples were taken at different
intervals, with spaces in between samples. This makes it easier to understand that DMM1 is sampling faster than DMM2.
Figure 77. Raw data in Excel
Figure 4. V and I curves with respect to time
Figure 5. Export menu
In Multi-tiled view, the trend chart is the only graphing view available.
You can set your bench layout to a single-tiled view and see the DMM’s
data as a histogram or table. You can toggle between multi-tiled view and
single-tiled view modes without needing to re-acquire your data. You can
do further analysis in single-tiled mode on the trend chart. Included in this
mode are measurement markers that allow you to analyze the measurement between the markers, similar to an oscilloscope. Customizable features such as auto scale, zoom, and trace color allow you to modify your
view of the data. You can annotate measurement events with in-program
notes too.
You can also set up asynchronous measurements. To enable this mode,
start with the single-tiled view. In the upper left-hand corner of the tile,
you will see an icon that allows you to open the bench tile in a new
window. This allows you to start the acquisition of this individual DMM
separately from the rest of your bench.
What if you want to use your own program to look at the data? Once the
measurements are finished, users can export the data into a variety of
formats, as shown in Figure 5. Formats include Microsoft Excel, Microsoft
Word, MATLAB, and .csv. The export menu also enables a quick screen
capture. Exported data includes time stamps that indicate when measurements were taken, as shown in Figure 6.
Figure 66. EExporting
Fi
i the
h ddata iinto a fil
file
3
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If you forget to save your data, Agilent’s DMM application can help. The
Data Manager (shown in Figure 8), accessed through the Manage Data
button, keeps track of data from past sessions. This data is stored in a file
on the PC and can be deleted or copied like other PC files. You can open
past data sessions and use the same DMM tools to analyze your data
just like if you had just acquired it. With this feature, you can go back 20
years and look at the measurements you made when you first started
using a DMM. A more practical use case would be to transfer groups of
measurements to another PC, then view the data in the familiar Agilent
DMM application.
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products, applications or services, please contact
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Figure 88. Data Manager
Summary
With the Agilent Digital Multimeter Connectivity Utility, you can
save time and effort. Benefits include:
• Measuring multiple signals synchronously is simpler than ever.
• Synchronize your measurements in minutes.
• Set up your DMM and gather data in less time than you would
spend for wiring up your measurement.
• Understanding your data just got easier; visualize it immediately
or export it to popular tools such as Excel or Word.
• Understanding your sampling is simpler when you can see if the
DMM’s are measuring at different intervals.
• Go deeper into your data by looking at each instrument’s mea
surements graphically or numerically without having to take the
data all over again.
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This application helps you use your equipment right away, without
the learning curve. Agilent’s DMM application is available for free
download from Agilent.com.
Product specifications and descriptions in this
document subject to change without notice.
© Agilent Technologies, Inc. 2013
Printed in USA, May 1, 2013
5991-2283EN
MEASUREMENT BRIEF
No Programming Required:
Digitizing Signals and
Analyzing Data with a DMM
Introduction
Snapshot
hot
Agilent digital multimeters are ubiquitous on work benches and in automated test systems. You have most likely used one at some point in time.
They measure basic electrical properties and give you a clear reading.
More sophisticated DMMs have higher precision, data logging capability,
and higher measurement speeds. If your DMM has these capabilities, you
can use it to digitize your signals. Digitizing is useful to understand your
signal better, and you can plot the data for a visual representation of your
signal. Digitizing with your DMM has been simplified with the Agilent
DMM Connectivity Utility.
A mechanical engineering student was designing an airplane wing for his fluid
dynamics class. In order to evaluate the flex of the wing under different conditions, he needed to be able to measure forces on the wing in at least four different locations. He had some force transducers that change resistance depending
on strain, these sensors were as old as he is. Since he is an undergrad, he did
not have access to the really expensive equipment that the Graduate students
use. He realized that he had access to the electronics’ lab equipment to borrow a
few DMMs. The student downloaded the Agilent DMM Connectivity Utility and
used the app to setup his measurement. He was going to take lot of discrete data
points then put the data together in Excel later. But he found out that he can use
this app to digitize all four points and graph the data right away. In an afternoon,
he’s able to digitize the tranducer outputs in parallel and sweep through all of the
test conditions. He then spent the rest of the weekend “studying”.
This measurement brief explains how the new Agilent DMM app can help
you digitize your signals and understand your data faster. In a couple of
clicks, it can graph your measurements. The app also synchronizes multiple
DMMs and allows you to put together a multichannel DMM system.
Simplified Digitizing
If you digitize your signals, you can analyze transients, non-repetitive
signals, and other AC waveforms in the time and frequency domains. You
use fast sampling techniques to understand your signals better. Focused
off-the-shelf solutions, such as a digitizer or high-precision scope, often
cost more than $10K and they may not offer the resolution you need for
your measurement.
A general-purpose DMM can digitize signals, but it is not the first instrument that comes to mind when you think of digitizing. Historically, DMMs
were set up to make discrete measurements with varying sample intervals.
Newer DMMs have deterministic sample intervals and sampling models
that allow for digitizing your signal. DMMs are flexible, have up to 22 bits
of resolution, and are relatively inexpensive. The DMM has the added
advantage of being able to digitize resistance, current, and temperature
straight out of the box. A new Agilent DMM software app makes it easier
to set up your test, gather your digitized data, and visualize it in the time
domain.
The app supports DMMs with digitizing capabilities which include the
34410A, 34411A, 34460A, and 34461A. The PC DMM app can communicate to these DMMs over GPIB, USB, or LAN. With this app you can
now use the same intuitive interface to set up digitizing for those DMMs.
Agilent’s DMM app will help you set up for your measurement functions.
The app presents the DMMs as bench tiles on your computer screen.
With this new app, you can now visualize signals on up to four different
DMMs at the same time. Using the application, you can control and make
measurements with up to nine DMMs.
MEASUREMENT TIP
#
1
Sample Intervals
When you use a DMM for data logging or digitizing, you
will want to minimize the variation in the timing between
samples. Eliminating the sources of additional delays can
improve the consistency between readings. The time required
for autoranging, range changes, auto zero, performing math
functions and updating the display can add to the variability
between measurements. See measurement tip “Improving
Digital Multimeter Throughput”, 5990-3218EN
Rather than insert a trigger delay between one sample and
the next, use a sample interval. A sample interval specifies
the time to wait after a trigger event has occurred before
making the next measurement. Using a DMM that allows you
to specify a sample interval instead of a trigger delay allows
precise sampling times, even when you are using features
such as autoranging and auto zero. For more information,
see “Data Logging and Digitizing Using a Digital Multimeter”,
5990-3220EN
F
Figure
1. Setting the sample interval specifies
tthe timing of the measurements rather than the
ddelay between samples.
Setup for Digitizing Measurements
To change parameters for each DMM, press the configuration wrench in
each tile. This brings up a Measurement menu and a Data logger/Digitizer
menu in tabbed windows. Let’s go through a simple example: digitizing
a simple waveform. The waveform we want to capture is a model of a
cardiac pulse.
In this example, we want to make DCV measurements. Use the Measurement menu to select DC Voltage as the measurement function. The
context-sensitive Measurement tab now presents you with all the parameters you would want to use for DCV measurements for your DMM. Figure
2 illustrates a typical setup for DCV measurements.
2
Display Measure Move
FFigure 2. DCV setup
MEASUREMENT TIP
#
2
Easier Connections
Use Agilent IO Libraries Suite to make identifying DMMs
connected to your PC easier. Instruments with direct
connections like USB and GPIB will auto-identify and
be recognized upon boot-up of the program. DMMs
connected via LAN and RS-232 require a configuration
step in Agilent Connection Expert, which you can access
through the DMM utility.
The Data Logger/Digitizer tab presents you with more advanced functionality such as data logging and digitizing setups. The content of this
context-sensitive menu is dependent on your DMM model. Under the
data logging menu you can find trigger menus, in-program limit testing
options and sample interval settings. New functionality allows you to set
up the apps to email you when a measurement exceeds a limit. Using this
mode, you can visualize live data as the measurements are taken.
Under the Digitizing menu, you’ll find the settings for the most common
digitizing configuration using a single trigger to sample multiple readings (see Figure 3). By using this menu, your sample interval is set to the
minimum value. In this mode, the samples are taken and stored inside the
DMM. After the data has been acquired, it is transferred to the app. This
minimizes any sample timing error due to data transfer rates.
Agilent DMM Connectivity Utility’s unified interface
supports Agilent DMMs released in the last 25 years.
It supports older models, including 34401A, 34405A,
34410A, and 34411A as well as our latest-generation
34450A, 34460A, and 34461A DMMs.
FFigure 3. Digitizer Configuration menu
As we mentioned earlier, you can set up your bench to digitize multiple
signals using this app. For more information see “No Programming Required: Multisignal Capture and Analysis with DMMs”, 5991-2283. After
setting up your digitizing configuration, pressing Start All Acquisitions will
start the measurements for all DMMs you have on your bench. Once you
have the data, you can visualize it using the app’s graph mode, as shown
in Figure 4.
Analyzing Digitized Data
Figure 44. Di
Fi
Digitized
i i d ddata
The Agilent DMM apps can help you understand your data visually in
real time. The application has a trend chart mode that displays your data
across time. This capability allows for a quick understanding of measurement peaks, noise, or drift. Similar to an oscilloscope, this mode features
measurement markers that allow you to analyze the measurement between the markers,. Customizable features such as autoscale, zoom, and
trace color allow you to modify your view of the data. You can annotate
measurement events with in-program notes too.
What if you want to use your own program to analyze data? Once the
measurements are finished, you can export the data into a variety of
formats (see Figure 5). Formats include Microsoft Excel, Microsoft Word,
MATLAB, and .csv. The export menu also enables a quick screen capture.
Exported data includes time stamps of when measurements were taken.
Figure 55. EExportt menu
Fi
3
www.agilent.com
www.agilent.com/find/DMMutilitysoftware
If you forget to save your data, Agilent’s DMM application can help. The
Data Manager (shown in Figure 6), accessed through the Manage Data
button, keeps track of data from past sessions. The data is stored in a file
on the PC and can be managed like other PC files. You can open past data
sessions and use the same DMM tools to analyze your data as if you had
just acquired it. With this feature, you can go back 20 years and look at
the measurements you made when you first started. You also can use this
capability to transfer groups of measurements to another PC, and then
view the data in the familiar Agilent DMM application.
For more information on Agilent Technologies’
products, applications or services, please contact
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Summary
Simple digitizing can be done using a DMM. The Agilent Digital
Multimeter Connectivity Utility enables you to save time and effort.
You can digitize multiple channels in parallel with synchronized
measurements and set up your DMM and gather data in less time
than you would spend wiring up your measurement. Understanding your data just got easier; you can visualize it immediately or
export it to popular tools such as Excel or Word. This application
enables you to use your equipment right away, without a long
learning curve. Agilent’s DMM application is available for free
download from Agilent.com.
Belgium
Denmark
Finland
France
32 (0) 2 404 93 40
45 45 80 12 15
358 (0) 10 855 2100
0825 010 700*
*0.125 €/minute
Germany
Ireland
Israel
Italy
Netherlands
Spain
Sweden
United Kingdom
49 (0) 7031 464 6333
1890 924 204
972-3-9288-504/544
39 02 92 60 8484
31 (0) 20 547 2111
34 (91) 631 3300
0200-88 22 55
44 (0) 118 927 6201
For other unlisted countries:
www.agilent.com/find/contactus
(BP-3-1-13)
Product specifications and descriptions in this
document subject to change without notice.
© Agilent Technologies, Inc. 2013
Printed in USA, May 2, 2013
5991-2284EN